Coherent and incoherent electromagnetic radiation emitted from a
channel-guided laser wakefield accelerator (LWFA) is calculated based on the
Lienard–Wiechert potentials. It is found that at wavelengths longer than the
bunch length, the radiation is coherent. The coherent radiation, which typically
lies in the infrared range, shows features that reveal details of the acceleration process and properties of the electron bunch, such as its duration, charge, energy, and offset with respect to the wakefield axis. It is found that the LWFA emits energy predominantly in the coherent range of frequencies. The incoherent range of the spectrum, which extends to the x-ray frequency range, consists of rather broad peaks caused by the acceleration. The radiated energy, power and the pulse duration are estimated.